However, they’re expensive, use up a province’s manufactory slot, and take a while to build. You really need to consider the long term when building ramparts. The most notable cases where ramparts would be crucial would be:
On borders with strong, massive neighbors that are hard to defeat On bottlenecks between impassable mountain ranges (e.g., the Alps, the Pyrenees, etc.)
Apart from those, you’ll likely expand beyond the provinces with ramparts. They can be good fallback positions, but then you’re not getting the most out of their value.
Ramparts Defensiveness
A rampart’s +15% defensiveness isn’t much on its own, but defensive modifiers are meant to be stacked to create an impregnable position. Build ramparts on hotly contested provinces that have these modifiers:
Attrition
Forts always inflict at least 1% attrition damage to besieging armies. Attrition modifiers are uncommon and are usually tied to difficult terrain and harsh climate. Ramparts are the only source that you have actual control over. When you stack them on a fort, you can drain more of your enemy’s manpower. This causes their war exhaustion to rise. High war exhaustion creates unrest and reduces manpower recovery. The first can potentially plague your enemy with rebels, while the second affects their ability to continue fighting. It also reduces their war enthusiasm. Low war enthusiasm means your enemy is more likely to accept a peace offer — even with unfavorable peace terms. If a powerful foe attacks you, the attrition damage from ramparts can help equalize the war in your favor.
